| Please note the following:
When Peach's baby was born she didn't talk yet. Princess Peach said she loves Mario as a brother.
Peach was supposed to be Mario's wife but She didn't. Mario broke up with Princess Peach (holding a baby) and never had a girlfriend again. Until Mario eventually got Rosalina as a new girlfriend and they married eventually.
Even though she hasn't been seen since, Baby Peach is alive and well. She's in the custody of her mother, as her father relinquished custody and is caring for his own child.